Postgres聚合条件总和

Question

我正在尝试总结 - 汇总条件产品的总重量（我希望这是有道理的）。我收到错误：

  

错误：聚合函数调用无法嵌套   第6行：，SUM（例如，当pc.type =＆＃39; TEES＆＃39;那么（SUM（opd.qt ...

这是查询摘录：

SELECT DISTINCT
         o.work_order_number dn
       , SUM(opd.qty) units
       , SUM (CASE  WHEN pc.type = 'TEES' THEN (SUM (opd.qty) * .75)
            WHEN pc.type = 'JERSEYS' THEN (SUM (opd.qty) * 1.5)
        END) AS weight

Answer 1

尝试：

SELECT o.work_order_number dn 
     , SUM(opd.qty) units 
     , SUM ( opd.qty * CASE pc.type 
                           WHEN 'TEES' THEN 0.75 
                           WHEN 'JERSEYS' THEN 1.5 
                       END ) AS weight
FROM ...
GROUP BY o.work_order_number

Answer 2

你可以做的就是嵌套你的选择语句E.g

select sum(weight),sum(etc) 
from (
    SELECT DISTINCT o.work_order_number dn 
                 , (opd.qty) units 
                 , ( CASE WHEN pc.type = 'TEES' THEN ((opd.qty) * .75) 
                          WHEN pc.type = 'JERSEYS' THEN ((opd.qty) * 1.5) END) AS weight)
).

因此，第一个选择语句包含你的case语句，第二个选择语句总结你的字段。